Methods for controlling well tools in well bores



Dec. 23, 1969 D. E. YOUNG 3,485,299

METHOD FOR CONTROLLING WELL TOOLS IN WELL BORES Original Filed Oct. 24, 1965 2 Sheets-Sheet l CONT/P01. 5 MfCf/A/V/JM I N VEN TOR.

BY flaw A rive/v5) Dec. 23, 1969 D. E. YOUNG 3,485,299

METHOD FOR CONTROLLING WELL TOOLS IN WELL BORES Oflginal Filed Oct. 24, 1965 2 Sheets$heet 2 Dav/ f. 7 0/7;

INVQUVTOR.

United States Patent 3,485,299 METHODS FOR CONTROLLING WELL TOOLS IN WELL BORES David E. Young, Houston, Tex., assignor, by mesue assignments, to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Original application Oct. 24, 1965, Ser. No. 504,885, now Patent No. 3,391,263, dated July 2, 1968. Divided and this application Oct. 18, 1967, Ser. No. 725,240

Int. Cl. E21b 7/00, 41/00 US. Cl. 166244 1 Claim ABSTRACT OF THE DISCLOSURE Methods and apparatus for use in controlling well tools disposed in fluid-filled well bores, including selectively positioning a switch and a movable pressure responsive switch actuator a predetermined distance apart from one another, said distance being the sum of the distance the actuator will be moved by hydrostatic pressure at a certain depth, plus an additional distance, lowering the switch and actuator into the well to said depth, and applying fluid pressure in addition to hyrostatic pressure to cause the actuator to actuate the switch.

This is a division of application Ser. No. 504,885, filed Oct. 24, 1965 now Patent No. 3,391,263.

This invention relates generally to oil well equipment and, more particularly, to a method and apparatus for actuating downhole well tools in a fluid-filled well bore.

In the drilling and completion of oil wells it is often desired to remotely actuate downhole tools by opening or closing an electrical circuit. Some examples of such tools are explosively actuated bridge plugs and packers, shaped charge casing perforators, or setting tools for various packers and plugs. One method of actuating such tools is to run the tool into the well bore on a special conductor cable so that the power source and switching mechanisms may be located at the earths surface. Other methods of tool actuation employ time control clocks which are subject to the disadvantage that they are beyond the control of the operator once the tool is lowered into the well.

The present invention concerns downhole actuation systems which can be controlled by the operator at the earths surface and do not require a conductor cable.

Accordingly, an object of the present invention is to provide a method and apparatus for remotely actuating downhole well tools having electrical circuitry without the use of a conductor cable extending from the tool to the earths surface.

A further object of the invention is to provide a method and apparatus for remotely actuating well tools in such a manner that actuation of the tool remains under the control of the operator at all times.

These and other objects of the present invention may be etfectuated by providing a pressure sensing means for actuating a well tool, which means is pre-set to require pressure in excess of the calculated or otherwise determined hydrostatic pressure at tool actuation depth. When the well tool with the associated pre-set pressure sensing means is lowered into the well bore to actuation depth, an additional controllable pressure is applied to the fluid in the well bore sufficiently in excess of the hydrostatic pressure to actuate the pressure sensing means and thus, the well tool.

One embodiment of a suitable apparatus for practicing the invention comprises the combination with well bore apparatus having electrical circuitry and which is adapted for insertion in a well bore containing fluid, of a housing having two chambers, one of which is open to hydro- ICC static well fluid pressure, and another chamber sealed from hydrostatic pressures. A spring-biased piston extends into both chambers and is movable in response to pressure differentials between the chambers. An actuator is attached to the piston for closing a switch upon a predetermined travel of the piston, and means are provided for adjustably positioning the switch.

The novel features of the present invention are set forth with particularity in the appended claim. The present invention, both as to its structural organization and utility together with further objects and advantages thereof, may best be understood by way of illustration and example of one embodiment when taken in conjunction with the accompanying drawings in which:

FIG. 1 is an elevational view, partially broken away, showing the general organization of the invention in connection with a well;

FIGS. 2A and 2B are longitudinal sectional views showing the details of construction of the control mechanism embodied in the present invention, FIG. 28 forming a lower continuation of FIG. 2A; and

FIG. 3 is a schemtaic view of an electrical system embodied in the present invention.

With reference to FIG. 1, numeral 11 indicates downhole well apparatus of the type which is actuated by manipulation of an electrical circuit. Examples of such apparatus are numerous and exemplified in Patents Nos. 3,155,164 (bridge plug), 3,057,295 (casing cutter), 2,873,675 (shaped charge perforator) and 2,760,583 (setting tool and packer). To the upper end of the tool 11 is threadably connected a battery case 12 containing a suitable power source such as a dry cell battery or the like. Generally indicated as numeral 13 is a control mechanism threadedly connected at its lower end to battery case 12 and at its upper end to connector sub 14, the entire apparatus being suspended in a well bore on a wire line 15. Well bore 16 contains the usual casing 17 which is filled with a column of well control fluid. Wire line extends upwardly through the customary wellhead 18 and lubricator 19, the wellhead having a side outlet 20 for connection with a suitable pump 21 whereby a controllable pressure may be selectively exerted on the column of fluid in the well bore.

The control mechanism 13, shown in detail in FIGS. 2A and 2B, is comprised of an upper housing member 22 having an internal chamber 23 which is open to hydrostatic well fluid pressures through port 24, and a lower tubular housing member 25 having an internal chamber which is sealed from hydrostatic well fluid pressures so as to be normally maintained at atmospheric pressure. Housing member 22 has an upper threaded part 26 for connection with sub 14. Near the upper end of chamber 23 is a support plate 27 which is held in abutting relationship with an upwardly facing shoulder 28 by suitable threaded ring member 29. Support plate 27 has ports 30 formed therein. If desired, a flexible diaphragm member (not shown) may be placed above the support plate 27 and upper chamber 23 filled with a hydraulic fluid for protection of the internal parts in the chamber from damage by well fluids. A spring connector member 31 having a bifurcated lower portion is threaded into support plate 27 centrally thereof and is securely anchored by a lock nut 32. A pin member 33 extends transversely between legs 34 of the bifurcated lower portion of the connector member 31 and the upper end of a spring 35 is hooked over pin 33.

The lower end of upper chamber 23 is closed by a packing sub 36 which is screw-threadedly engaged with the lower portion 37 of upper tubular housing member 22. An O-ring 38 is positioned in a suitable groove in the periphery of packing sub 36 and seals against the inner wall of housing member 22. Formed centrally in sub 36 is a bore 39 which slidably receives a pressure differential responsive means in the form of an elongated piston member 40, one end of the piston member extending into upper chamber 23. An O-ring 41 is positioned in a groove in sub 36 and seals against the exterior of piston member 40.

Another spring connector member 42 is threadedly secured to the upper end of piston member 40. The lower end of the above-mentioned spring 35 is suitably attached to connector member 42 by a pin 43 extending between the upwardly extending legs of the connector member.

The lower tubular housing member 25 is threadedly connected as at 44 to the lower portion of upper tubular housing member 22 and extend downwardly therefrom to form a lower chamber 45. A seal ring 46 seals the threaded joint between the upper and lower tubular housing members. The lower end portion of piston member 40 extends downwardly into lower chamber 45. T hreadedly coupled to the lower end of the piston member is a con nector 47 for a depending switch actuator in the form of a plunger member 48 made of a suitable electrically nonconductive material.

An upper portion of lower housing member 25 is counterbored at 49 to form an upwardly facing shoulder 50. An upper annular electrical insulation ring 51 made of a suitable nonconductive synthetic resin is received between shoulder 50 and the lower end face 52 of housing member 22. A lower portion of housing member 25 is counterbored at 53 to form a downwardly facing shoulder 54. A lower annular electrical insulation ring 55 is held in place against shoulder 54 by a retainer member 56. Received between the two insulation rings are circumferentially oppositely spaced conductor rails 57 made of copper or other electrically conductive material, the ends 58 of conductor rails 57 being received in slots 59 formed in the lower and upper faces of the insulation rings 51 and 55.

Slidably and adjustably mounted on each conductor rail is a contact carriage 60 which is adapted for selective vertical positioning along a conductor rail and to be held in such selected position by a set screw 61. Each contact carriage carries an elongated resilient electrical contact member 62 which extends radially inwardly in overlapping relationship with the other of the contact members. It will' be appreciated that the conductor rails 57 perform the functions of adjustably supporting and positioning the contact carriages as well as serving as an integral part of a series electrical circuit. Suitable indicia 63 are provided on the conductor rails to aid in selectively spacing the contacts a predetermined distance below the switch actuator 48.

Near the lower ends of conductor rails 57 are terminals 64 adapted for connection with insulated electrical conductor wires. One wire 66 extends to a terminal on battery 67. Another wire 68, in combination with wire 69 connec'ted to the other of the battery terminals, provide leads to'well tool 11. As will be readily apparent, sufficient downward travel of the piston member 40 will cause plunger member 48 to engage and close resilient contact members 62, thus completing a series electrical circuit comprised of power source 67, wires 66, 68, 69, conductor rails 57, contact carriages 60 and contacts 62 for actuation of well tool 11. It will be noted that the threaded joints between battery case 12, lower tubular housing member 25, and well tool 11 are sealed by O-rings 70 so that lower chamber 45 is sealed from hydrostatic well fluid pressures.

In the practice of the method and operation of the apparatus, the actuation depth (commonly determined by various logging operations) and the weight of the fluid in the well bore are known and the hydrostatic well fluid pressure at such depth can be readily calculated. Since lower chamber 44 of the control mechanism is maintained at atmospheric pressure by being sealed from well fluid pressure, and since upper chamber 23 is open to well fiuid pressure at p rt 24, the pressure difierential across piston member 40 at tool actuation depth is easily determined. The effective area of piston member 40 and the spring constant for tension spring 35 are known. With these factors the distance that the piston and plunger 47 will move downwardly into the lower chamber 45 when the tool is low-cred to actuation depth is readily calculated.

So that actuation of the well tool 11 will remain under the control of the operator at all times, and for the further purpose of preventing premature closing of the electrical contacts due to such variables as shock pressure loads, temperature variations and mechanical inaccuracies in the device, the contact carriage members 60 with attached contacts 62 are selectively positioned during assembly and set along conductor rails 57 the above-mentioned distance plus an additional distance away from actuator 48. Thus, merely lowering the tool in the well bore to actuation depth will not cause the plunger to move downwardly enough to close contacts 62. An additional controllable pressure must be exerted on the fluid column in the well casing to provide a sufiicient pressure differential across piston member 40 so that the actuator will move down the total preset distance and close the contacts. With the control mechanism thus preset to sense hydrostatic well fluid pressure plus an additional controllable pressure, the tool is lowered into the well to actuation depth. When the operator desires to actuate the well tool 11, the additional controllable pressure is applied to the column of fluid in the casing 17 by means of the previously mentioned pump 21. The actuator 48 will then move down the additional distance and close contacts 62, thus closing the electrical circuit and actuating the tool.

It will be appreciated, of course, that the additional pressure may be selectively applied and released by the operator which will result in stroking the piston to close and open the switch repeatedly. Therefore, the electrical circuitry in well tool 11 may include a plurality of electrical circuits which can be sequentially operated by a means responsive to the selective application and release of the additional controllable pressure. Such an arrangement is shown schematically in FIG. 3. One of the previously-mentioned contacts 62 of the control mechanism 13 shown in FIG. 2 is electrically connected to the power source 67. The other of the contacts 62 is electrically connected to the coil 71 of a stepping switch 72, the coil being electro-mechanically coupled to a common switch arm 73 in a known manner. Common terminal 74 of stepping switch 72 is also supplied with power from source 67 and is movable from a position of coaction with a dead terminal 1 during running in to positions of coaction with output terminals 2-4 and eventually to reset terminal 5. Thus, each time the contacts 62 are closed by actuator 48 (FIG. 2) an electrical pulse from source 67 through control mechanism 13 is etfective to advance the common switch arm 73 sequentially from one terminal to the next for operating each of a plurality of circuits A, B, C in well tool 11. By way of example, elements A, B, C in FIG. 3 may be circuits including squibs to be fired for sequential actuation of a plurality of shaped charge devices in a casing perforator.

As further shown in FIG. 3, a time delay means D may be electrically connected between the control mechanism 13 and the stepping switch 72, the delay circuit requiring a contant amplitude input signal for a given time duration (one second for example) before an output signal is generated to actuate the stepping switch 72. The delay circuit provides a safety factor against premature actuation of circuits A, B, C due to shock pressure loads which may act to close contacts 62 in control mechanism 13. These circuits cannot be fired unless the additional controllable pressure is selectively maintained by the operator to keep the contacts 62 closed for the time duration inherent in the operation of delay means D.

Certain modifications of an obvious nature may be made in the apparatus illustrated. For example, contacts 62 may be replaced by a microswitch with conductor wires leading directly therefrom to other elements in the circuit, in which case only one support rail would be needed. Of course, the support rail would not, in this case, form a part of the electrical circuit as in the illustrated embodiment. It will also be appreciated that the control mechanism is adapted to be run into the well conduit on a tubing string.

It will be observed from the foregoing that applicant has provided a method and apparatus for actuating downhole well tools wherein the electrical circuitry of the tool may be manipulated without the use of a conductor cable extending from the tool to the earths surface and wherein the actuation of the tool will remain under the control of the operator at all times. Since certain changes may be made in the above-disclosed method and apparatus without departing from the scope of the inventive concept involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A method of selectively actuating a switch at a certain depth in a well bore containing a column of fluid, comprising the steps of: setting the switch a predetermined distance away from a switch actuator which is movable in response to sensed well bore fluid pressures, said distance being the sum of a predetermined distance the actuator will travel responsive to sensed hydrostatic well fluid pressure at said certain depth, plus an additional distance lowering the switch and switch actuator into the well bore to said certain depth; and applying a pressure in addition to the hydrostatic well fluid pressure to move the actuator the additional distance whereby said switch actuator will actuate said switch.

References Cited UNITED STATES PATENTS 3,011,551 12/1961 Young et a1 1754.54 X 3,040,808 6/1962 Schramm et al. 1754.54 X 3,185,224 5/1965 Robinson 1754.54 3,189,094 6/1965 Hyde 16655.1 X 3,208,355 9/1965 Baker et al. 166120 X 3,227,228 1/1966 Bannister 1754.54 X

DAVID H. BROWN, Primary Examiner U.S. CI.X.R. 166--65 

